Concentration and Solvent Dependence of the Hierarchical Organization of Asphaltenes in Solution.

Asphaltenes are a group of planar molecules found in crude oil and are prone to aggregation which often causes blockage of pipes along the oil production stream. Asphaltene concentration and solvent composition on the hierarchical structure of asphaltenes in solution was studied using small-angle x-ray scattering (SAXS). SAXS, a technique to study nanostructure was used to study modified asphaltenes with polar groups removed at concentrations of 1, 5, 10, and 50 mg/ml in toluene. After collecting scattering data on a 2-D detector, SASView was used to analyze the results by fitting them with a mass fractal model over a Q-range: 0.008 - 0.4 Å^-1. Results will be compared and integrated with statistical mechanics theories such as the DLVO (Derjaguin–Landau–Verwey–Overbeek) theory that models absorption and the aggregation of nanoparticles in aqueous systems and describes the stability of colloidal dispersions. Future work will include the use of other solvents, as well as the impact of pressure and temperature on the nanostructure of these systems.